1. Field of the Invention
The present invention relates to a method, system, and program for processing a packet including I/O commands and data
2. Description of the Related Art
In storage environments, data access commands are communicated from a host system to a storage controller, which manages access to the disks. The storage controller may be a card inside the host system or a separate device. The Internet Small Computer Systems Interface (iSCSI) protocol is used for storage networks that utilize Ethernet connections, including Ethernet switches and routers. The term “iSCSI” as used herein refers to the syntax and semantic of the iSCSI defined by the IETF (Internet Engineering Task Force) standards body, and any variant of that protocol. In current storage networks where iSCSI is utilized, the packet configuration comprises an Ethernet package encapsulating an Internet Protocol (IP) and Transmission Control Protocol (TCP) package layers, which further encapsulate an iSCSI package that includes one or more SCSI commands. The Ethernet protocol provides for link-level error checking as the packets flow from point-to-point on any network segment (link) to determine whether data has been corrupted while passing on a link. In network data transmission operations, an initiator device transmits data or commands over the network to a target device. The TCP/IP package includes an error correction code to perform an end-to-end checking to determine at the opposite end whether the transmitted packet has changed during the transmission as the packet passes through switches and routers. A receiving device detecting an error will send a negative acknowledgment to the sending device to request retransmission of those packets in which errors were detected.
Both an initiator of such an iSCSI command and the target must include code for the Ethernet, TCP/IP, and iSCSI protocols when processing each part of the transmitted package. The target device, upon receiving the packet, will use the Ethernet protocol to access the TCP/IP package, then use the TCP/IP protocol to access the iSCSI package, and then use the iSCSI protocol to access the SCSI commands within the iSCSI package.
Many manufacturers that want their devices to participate in an iSCSI environment must provide controllers capable of processing the Ethernet, TCP/IP and iSCSI protocols. Such capability requires that the processor include sufficient computational resources and power to execute all the communication protocols. Such code may be quite costly for limited controllers, like storage disk controllers.
Accordingly, there is a need in the art for improved techniques for transmitting packets of data over a network, such as a small network where packet reordering, or out of order reception is not an issue.